One of the biggest free-agent additions of the summer of 2007 came not on the court but on the sideline. Tom Thibodeau, long Jeff Van Gundy's right-hand man in New York and Houston, left the Rockets after Van Gundy's departure and joined Doc Rivers in Boston to take responsibility for the Celtics' defense. While Ray Allen and Kevin Garnett are the most important newcomers in Boston, Thibodeau deserves credit for molding the team's several new parts into a cohesive defensive unit that ranks as one of the best in modern NBA history.

Earlier this season, I took a look at the Celtics defense and noted that, measured by Defensive Rating relative to league average, Boston was playing the best defense since 1973-74, when the league began tracking turnovers, allowing us to calculate per-possession defensive ratings. The Celtics have slipped slightly from that lofty perch, but not far. Their Defensive Rating is now 8.8 percent better than league average, which would rank them second in NBA history behind the 2003-04 Spurs, who were 9.3 percent better than league average.

So, during media availability at the All-Star Game in New Orleans, I avoided the reporters flocking to Kobe Bryant and LeBron James and sought out Thibodeau (idly chatting with a member of Houston's PR staff) to talk defensive philosophy, the individual talents of many of the Celtics, and more.

Kevin Pelton: Over the course of your career, you've been associated with a number of outstanding defensive teams. How does this year's Celtics team compare to the best of those?

Tom Thibodeau: Right now, I'd say the New York teams were much more physical because at that time you were allowed to play much more physical and we had greater size. This team is probably a little bit more versatile. We have guys that can play multiple positions and I think Garnett makes us very unique because of his ability to guard multiple positions. Then a guy like [James] Posey is a terrific team defender, so he gives us that balance there. There's room for improvement with our team right now. We're still moving along and we have to be able to sustain it over the course of the season and obviously carry that through the playoffs. Each and every day, we're still working at it.

KP: This Celtics team ranks amongst the league leaders in steals, while most of your teams have not forced a lot of turnovers or come up with a lot of steals. How is this group different?

TT: It's still the same type of defense that we've always played. Our big thing is to get back, get set, apply hard ball pressure, keep the ball out of the paint, challenge shots and then finish your defense with the rebound. Once we do those things, we want to also use our instincts and [Rajon] Rondo's terrific at reading the ball and getting into passing lanes and that sort of thing, so we want to take advantage of those skills. And of course Garnett is terrific at extending the defense, so we move up the floor with him. I think you combine all those things and the fact that our three top players--Kevin, Paul [Pierce] and Ray are committed to defense, so each and every day they practice hard. They don't take any practices off...a guy like [James] Posey [either], all those guys. Their commitment--and it started from day one--is really what set the tone for us.

KP: How much does it help you to have the star players buy in to the importance of defense?

TT: That's the big thing, I think. From day one, Doc sold the vision about how important defense was going to be. Kevin, Ray and Paul have been terrific carrying that vision out. I think when your three top players practice hard every day and commit to doing it, I think it leads to everyone else following it. We have experienced veterans that have also come from very good defensive teams. When you look at a Posey and an Eddie House, those guys are committed to playing strong defense. Then when you look at a guy like [Kendrick] Perkins, who oftentimes gets overlooked--his size and his ability to shut down the lane is critical. Rondo, his ability, his quickness is so important for us.

KP: How much does Rondo's ability to pick up the ball full court help your defense?

TT: A lot. He has a lot of responsibility with our defense. Obviously, when the ball is shot, he has to protect our basket first and then come up the floor. He's been able to do both. He sets the tone. What he's doing on the ball really sets the tone for our defense. He's gotten better and better at his ball pressure. His individual and team defense has continually improved as the season has gone along. And I think he's doing a great job of running our team. So I think he sees his responsibility to run the team, to play great defense and then take the opportunities that he has to hit the paint, get in the lane and take the spot-up shots. He's done that consistently for the last two months of the season.

KP: How unique is Garnett's ability to step out to defend the pick-and-roll and get back to his man or switch if needed?

TT: The thing that I think makes Kevin so special is that he's a multiple-effort guy. He can do several different things on the same possession. He has the ability to show on a pick-and-roll, get back into the lane, make the next rotation, challenge a shot, go get a rebound. Oftentimes you see him making two, three and four efforts on the same possession. I think, in order to be a great defensive team, that's the type of mindset that you have to have.

KP: Were you surprised by how Glen Davis was able to hold Tim Duncan in check last Sunday and what he's done defensively this season? (The week before the All-Star break, as detailed by John Hollinger, Davis defended Duncan down the stretch in a 98-90 Boston win over San Antonio at TD Banknorth Garden without Garnett or Perkins.)

TT: I'll be honest, it hasn't surprised me because I watched him from day one. He has surprised me, I take that back, in some ways because he's much more advanced than I thought. In terms of being a rookie, he's not only pretty good individually but he's very good team-wise. The thing that I think makes him so special is the fact that he combines strength with great lateral quickness, so he has the ability to hold his position and defend the post-up and he also has the ability on pick-and-rolls to show, get back into the play and things like that. I think his strength, along with his lateral quickness, has been a great asset for him, but usually it takes rookies a little bit longer to understand what team responsibilities they have to fulfill and he's picked that up really quickly. So I would say that part has surprised me.

KP: How do you evaluate a defense?

TT: You're constantly evaluating your defense in terms of one, your ability to get back and your floor balance; you don't want to give up easy baskets. Then you want to keep the ball out of the paint. Then you want to evaluate whether you're challenging shots properly, whether you're rebounding the ball well enough. Then you look at your schemes to make sure that you're executing those things correctly. It's a constant battle, because you can't work on everything but you're trying to build all those habits that make you have a consistent defense. You're always working defensive transition, pick-and-roll defense, low-post defense, one-on-one defense. It comes down to the basic premise of keeping the ball out of the paint. We feel if you take easy baskets away and force teams to shoot contested twos, then you're going to have a good defense.

KP: What role do numbers, including those you track yourselves (like deflections or contested shots) play in that evaluation?

TT: We track everything, because I think it gives you a gauge of where you are defensively. You may have a number of games in a row where you're not practicing a lot and you see there's slippage, so you have to try to correct those things in your walkthroughs, in your team meetings and things like that. You're studying all the time, watching film, but then you're using those numbers to either confirm or let you know that this is an area that we need to work more on or make some corrections in.

KP: As you move toward the playoffs, what is going to be important for you guys?

TT: In the playoffs, you have to have a balanced team. You have to play well on offense and defense. You can't be just good in one area. We want to be good in both areas. We're balanced. We want to make sure that we're a low-turnover team, that we're taking high-percentage shots. We want to play inside-out. Those are the things that we work on every day. When you look at the playoffs and watch how teams play, often the first thing that will be taken away is transition. Then it comes down to your execution. So you have to be good in transition and then you also have to be good in a halfcourt set. Just as important is your defense. I think you have to be strong in all areas of your game to advance in the playoffs, so each and every day that's what we strive to work on. We want to continually improve as the season goes along. We're trying to build the right habits that will make us successful in the playoffs.

Kevin Pelton is an author of Basketball Prospectus.
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